Itō Jinsai founded the Kogaku ("Ancient Learning") approach to Japanese Confucianism, arguing in his "Gomō jigi" (The Meaning of Words in the Analects and Mencius) that careful philological attention to the original language of Confucius and Mencius could recover meanings obscured by later Song-dynasty Neo-Confucian metaphysics. He is often described as simply rejecting Zhu Xi, but he retained and reworked a metaphysics of material force (ki) and principle (ri), disputing Zhu Xi chiefly over their relative priority.
Intellectual setting
Jinsai taught in Kyoto during the early Tokugawa period, when Neo-Confucian scholarship was becoming institutionally central to Japanese intellectual life, and his private academy offered an alternative to officially sponsored Zhu Xi orthodoxy, training students through direct textual engagement with the classics.
Key ideas
Philological return to the ancient texts
In the "Gomō jigi," Jinsai analyzed the precise meanings of core Confucian terms as used by Confucius and Mencius themselves, arguing that later commentators had layered on metaphysical meanings not clearly grounded in the original texts.
The priority of vital force (ki) over principle (ri)
Rather than rejecting Zhu Xi's metaphysics outright, Jinsai reworked it, arguing that dynamic material force (ki) is metaphysically prior to and generative of principle (ri), reversing the priority Zhu Xi had given to principle as a separate, transcendent ordering reality.
Legacy
Jinsai is regarded, alongside the later Ogyū Sorai, as a founding figure of the Kogaku movement in Tokugawa Confucianism, and his philological method influenced subsequent Japanese Confucian and nativist (kokugaku) scholarship's turn toward direct textual study.